Anchor for hollow walls

ABSTRACT

An anchor ( 910 ) for mounting to a hollow wall (W) made of friable material comprises a proximal flanged end ( 918 ) adapted to be engaged by a rotatable tool (B) to rotate the anchor ( 910 ) about a longitudinal axis (A) thereof and to cause is to gradually engage the wall (W). The anchor ( 910 ) also includes a distal end ( 912 ) adapted to cut through the wall (W) as the anchor ( 910 ) is rotated, and a shank ( 920 ) extending between the proximal and distal ends ( 918, 912 ). The shank ( 920 ) includes at least one expandable leg ( 924 ) that is in a collapsed position thereof when the anchor ( 910 ) is rotated to mount it to the wall (W) and that is located distally beyond a non visible surface of the wall (W) once the anchor ( 910 ) has been mounted to the wall and is in a first position thereof. The wall anchor ( 910 ) includes an outer thread ( 922 ) that securely engages the wall (W). A threaded fastener (B), e.g. a screw, is adapted to be introduced in the anchor ( 910 ) and to threadably engage the same distally of the leg ( 924 ) such that sufficient rotation of the threaded fastener (B) retracts the distal end ( 912 ) towards the proximal end ( 918 ) thereby causing the leg ( 924 ) to displace to a laterally expanded position thereof and to engage the non visible surface of the wall (W).

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional Application is a continuation of U.S.Non-provisional application Ser. No. 12/693,976, entitled “ANCHOR FORHOLLOW WALLS,” filed on Jan. 26, 2010 and issued as U.S. Pat. No.9,353,782, which is a division of U.S. Non-provisional application Ser.No. 10/538,451, entitled “ANCHOR FOR HOLLOW WALLS,” filed on Jun. 10,2005 and issued as U.S. Pat. No. 7,654,781, which is a National StageEntry of International Application No. PCT/CA03/02041, filed on Dec. 11,2003, which claims priority to U.S. Provisional Application No.60/435,369, filed Dec. 23, 2002, the entireties of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wall anchors and, more particularly, toself-drilling anchors for use typically in hollow walls made of friablematerials, e.g. plasterboard, gypsum, etc.

2. Description of the Prior Art

The Ernst et al, Gianuzzi and McSherry U.S. Pat. Nos. 4,601,625,5,234,299 and 5,529,449, respectively, each disclose an anchor which isturned in a wall made of friable material and is retained in the wall byvirtue of the friable material being compressed between the root anddeep thread spiraled along the cylindrical body of the anchor andbetween the proximal end of the thread and flanged end of the anchorwhich becomes embedded in the front surface of the wall. A work piece isthen fastened to the wall by a screw fastener that is screwed into thevisible open end of the anchor and holds the workpiece between theflanged end of the anchor and the head of the screw fastener.

Toggle bolts are also known, such as in U.S. Pat. No. 6,435,789 issuedon Aug. 20, 2002 to Gaudron. Generally a self-drilling toggle anchorincludes a drilling member and a toggle member. The drilling member isadapted to drill through the wall hole with the toggle member in itsretracted position, i.e. extending axially along the drilling member,whereby the whole anchor is inserted longitudinally in the wall with thetoggle member being located completely behind the wall. The togglemember defines a threaded opening that extends transversallytherethrough and that has, in the retracted position of the togglemember, its axis perpendicular to the drilling member and to thelongitudinal orientation of the whole anchor when it drilled into thewall. In a second step, a screw is rotatably inserted in the anchor and,at one point, a tip of the screw engages the toggle-member and causes itto pivot an extended position thereof, wherein the toggle member extendsat right angles to the drilling member and to the general orientation ofthe anchor. The screw then engages the threaded opening of the togglemember. Once the head of the screw abuts the front of the wall or thehead of the anchor, it cannot displace longitudinally, such that furtherrotation of the screw draws the toggle member translationally towardsthe head of the screw and thus towards the rear face of the wall untilis abuts firmly the same, whereby the anchor is fixed to the wall.Alternatively, the drilling tip can be provided on the toggle member,and in such cases the above drilling member remains similar in that itfixedly depends from the anchor head but it does not perform thedrilling action. Such designs are somewhat costly, as the anchorrequires two distinct components (e.g. the above drilling and togglemembers) that also must be assembled together.

SUMMARY OF THE INVENTION

It is therefore an aim of the present invention to provide an improvedanchor adapted to be securely mounted to a hollow wall such that an itemcan be attached thereto, e.g. via an elongated fastener engaged in theanchor.

Therefore, in accordance with the present invention, there is providedan anchor for mounting to a hollow wall, comprising a proximal endadapted to be engaged by a rotatable tool to rotate said anchor about alongitudinal axis thereof and to cause it to gradually engage a wall, adistal end adapted to cut through the wall as said anchor is rotated,and a shank between said proximal and distal ends, said shank includingat least one expandable leg, said expandable leg being in a collapsedposition thereof when said anchor is rotated to mount it to the wall andbeing located distally past a rear surface of the wall once said anchoris mounted to the wall, said anchor including outer threads, said anchorbeing adapted to receive therein a threaded fastener and to threadablyengage the same distally of said leg such that sufficient rotation ofthe threaded fastener retracts said distal end towards said proximal endthereby causing said leg to displace to a laterally expanded positionthereof.

Also in accordance with the present invention, there is provided ananchor assembly for mounting to a hollow wall, comprising a threadedfastener and an anchor; said anchor including a proximal end adapted tobe engaged by a rotatable tool to rotate said anchor about alongitudinal axis thereof and to cause it to gradually engage a wall, adistal end adapted to cut through the wall as said anchor is rotated,and a shank between said proximal and distal ends, said shank includingat least one expandable leg, said expandable leg being in a collapsedposition thereof when said anchor is rotated to mount it to the wall andbeing located distally past a rear surface of the wall once said anchoris mounted to the wall, said anchor including outer threads, said anchorbeing adapted to receive therein said threaded fastener and tothreadably engage the same distally of said leg such that sufficientrotation of said threaded fastener retracts said distal end towards saidproximal end thereby causing said leg to displace to a laterallyexpanded position thereof

Further in accordance with the present invention, there is provided ananchor for mounting to a hollow wall, comprising a proximal end adaptedto be engaged by a rotatable tool to rotate said anchor about alongitudinal axis thereof and to cause it to gradually engage a wall, adistal end and a shank between said proximal and distal ends, said shankincluding at least one expandable means, said expandable means being ina collapsed position thereof when said anchor is rotated to mount it tothe wall, said anchor including outer threads, said anchor being adaptedto receive therein a threaded fastener and to threadably engage the samedistally of said expandable means such that sufficient rotation of thethreaded fastener retracts said distal end towards said proximal endthereby causing said expandable means to displace to a laterallyexpanded position thereof behind the wall.

Still further in accordance with the present invention, there isprovided a method for mounting an anchor to a hollow wall, comprisingthe steps of:

a) providing a hollow anchor including outer threads and having aproximal end, a distal end and a shank between said proximal and distalends;

b) installing said anchor in a wall; and

c) rotatably driving a threaded fastener in said anchor such that saidthreaded fastener engages distal end and causes, once said fastenercannot further advance translationally in said anchor, said distal endto retract towards said proximal end thereby deforming said shank suchthat said shank laterally expands behind the wall.

Still further in accordance with the present invention, there isprovided a method for forming inner threads in a hollow anchor adaptedfor a hollow wall, comprising the steps of:

a) providing a core pin having outside threads thereon;

b) molding an anchor in a mold with said core pin therein such that saidcore pin is at least partly surrounded by plastic; and

c) translationally removing said core pin, without substantiallyrotating it, from the molded anchor without stripping the female threadsformed by said core pin in said anchor.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the nature of the invention, referencewill now be made to the accompanying drawings, showing by way ofillustration a preferred embodiment thereof, and in which:

FIG. 1 is a schematic side view, partly in cross section, showing afirst wall anchor in accordance with the present invention, engaged intoa wall and in a collapsed position thereof;

FIG. 1a is an end view of the wall anchor of FIG. 1;

FIGS. 1b and 1c are end views of variants of the wall anchor of FIGS. 1and 1 a;

FIG. 2 is a schematic side view, partly in cross section, that issimilar to FIG. 1, but shows the wall anchor of FIG. 1 in an expandedposition thereof;

FIG. 2a is an end view of the wall anchor of FIG. 2;

FIGS. 2b and 2c show the variants of FIGS. 1b and 1c in the secondposition of the wall anchor;

FIG. 3 is a schematic side view, partly in cross section, of a secondwall anchor in accordance with the present invention, which is similarto FIG. 1 and which is shown in a collapsed position thereof;

FIGS. 3a to 3c are similar to FIGS. 1a to 1c , but pertain to the wallanchor of FIG. 3;

FIGS. 4 and 4 a to 4 c are similar to FIGS. 2 and 2 a to 2 c, butpertain to the second wall anchor of FIG. 3 that is shown in an expandedposition thereof;

FIG. 5 is a schematic side view, partly in cross section, of a thirdwall anchor in accordance with the present invention, shown in acollapsed position thereof;

FIG. 5a is an end view of the wall anchor of FIG. 5;

FIG. 6 is a schematic side view, partly in cross section, of the wallanchor of FIG. 5, but showing the wall anchor in an expanded positionthereof;

FIG. 6a is an end view of the wall anchor of FIG. 6;

FIGS. 7 and 7 a to 7 c are similar to FIGS. 1 and 1 a to 1 c, but show afourth wall anchor in accordance with the present invention and in acollapsed position thereof, with FIG. 7 being a cross-sectional view;

FIGS. 8 and 8 a to 8 c are similar to FIGS. 2 and 2 a to 2 c, butpertain to the wall anchor of FIG. 7 that is shown in an expandedposition thereof, with FIG. 7 being a cross-sectional view;

FIGS. 9 and 9 a to 9 c are similar to FIGS. 1 and 1 a and 1 c, but showa fifth wall anchor in accordance with the present invention and in acollapsed position thereof;

FIGS. 10 and 10 a to 10 c are similar to FIGS. 2 and 2 a to 2 c, butpertain to the wall anchor of FIG. 9 that is shown in an expandedposition thereof;

FIG. 11 is a schematic side view, partly in cross section, of a sixthwall anchor in accordance with the present invention, shown in acollapsed position thereof;

FIG. 12 is a view similar to FIG. 11, but shows the sixth wall anchor inan expanded position thereof;

FIG. 13 is a side view, partly in cross section, that is similar to FIG.1, but shows a seventh wall anchor in accordance with the presentinvention and in a collapsed position thereof;

FIG. 14 is a side view, partly in cross section, of the wall anchor ofFIG. 13, but in an expanded position thereof;

FIG. 15 is a side view, partly in cross section, of an eighth wallanchor in accordance with the present invention, shown in a collapsedposition thereof;

FIG. 16 is a side view, partly in cross section, of the wall anchor ofFIG. 15, but shown in an expanded position thereof;

FIG. 17 is a side view of an anchor section of the wall anchor of FIG.15;

FIG. 18 is a side view of a locking member of the wall anchor of FIG.15;

FIG. 19 is a schematic side view of a ninth wall anchor in accordancewith the present invention, also shown being a molding pin used in themanufacture of the ninth anchor;

FIG. 20 is an end view of the wall anchor of FIG. 19;

FIG. 21 is a cross-sectional view of the wall anchor of FIG. 19;

FIG. 22 is a side view of a tenth wall anchor, similar to that of FIG.3, and also in accordance with the present invention;

FIG. 23 is an end view of the tenth anchor of FIG. 22;

FIGS. 24, 25 and 26 are cross-sectional views taken respectively alonglines 24-24, 25-25 and 26-26 of FIG. 22;

FIGS. 27a to 27d are successive partly cross-sectional side viewsshowing the installation of the tenth anchor of FIG. 23 into a wall;

FIGS. 28 and 29 are respectively a side view and a longitudinalcross-sectional view of the tenth anchor of FIG. 23 provided with a corepin therein that is used during the molding thereof;

FIGS. 30 and 31 are respectively a side view and a partlycross-sectional view of part of the core pin.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, FIG. 1 illustrates a wallanchor 10 in its first, i.e. insertion, position, with FIG. 1 showingthe wall anchor 10 fully inserted through a wall W and with a screw Sengaged in the wall anchor 10 and holding an item I against the wall W.In FIG. 2, the wall anchor 10 is shown in a second, i.e. expanded,position thereof wherein the wall anchor 10 is further secured to thewall W, as explained in details hereinafter. The wall anchors describedherein are generally all made of plastics material, e.g. nylon.

The wall anchor 10 is hollow, for receiving the screw S therein, andcomprises a pointed distal tip 12 provided with a partial thread 14therearound and defining an opening 16. Proximally, the wall anchor 10includes a head 18 and, between the head 18 and the distal tip 12, thewall anchor 10 comprises a shank 20. The proximal portion of the shank20 includes a thread 22 and, between the threads 14 and 22, the shank 20includes a system of expandable legs 24. In the embodiment shown inFIGS. 1 and 2, the shank 20 includes four such legs 24 which, in thecollapsed position of FIG. 1, are linked together by frangible films 26,although such films can be absent, in which case the legs 24 extendalong side each other but are not connected together.

The head 18 can be engaged by a torque driven rotational tool, such as ascrewdriver, manual or powered. For instance, the head 18 can define acruciform recess (see reference 819 in FIGS. 20 and 919 in FIG. 23) forreceiving a Phillips-type screwdriver bit. This allows the wall anchor10 to be rotatably driven, as a screw, through the wall W, with thedistal tip 12 assisting in penetrating the wall 10 and with the threads14 and 22 consecutively engaging the friable material of the wall W and,in fact, tapping the same such that the wall anchor 10 is secured to thewall by way of the threads 22. The opening 16 assists in evacuating thefriable material that has been removed from the wall W by the wallanchor 10. Once the wall anchor 10 is in its position shown in FIG. 1with respect to the wall W, the screw S, with or without the item Ilocated between the head of the screw S and the front or visible surfaceof the wall W, is rotatably engaged into the wall anchor 10 until itassumes its position shown in FIG. 1.

Once the head of the screw S cannot further axially translationallyadvance (in FIG. 1 because of its abutment with the item I, oralternatively because it has engaged the head 18, or even the visiblesurface of the wall W), further rotation of the screw S causes thedistal tip 12 of the wall anchor 10 to be pulled towards the wall W inview of the threaded engagement between the screw S and the wall anchor10, typically at section 28 thereof that has been tapped by the screw S(although female threads may alternatively have been formed by moldingwithin the section 28). The gradual retraction of the distal tip 12towards the head 18 causes the legs 24 to outwardly expand and,initially, any frangible film 26 between adjacent legs 24 is ruptured.

Each leg 24 has a shorter proximal portion 30 and a longer distalportion 32 that connect at pivot 33. The expansion of the legs 24 isinterrupted by the proximal leg portions 30 abutting the rear ornon-visible surface of the wall W, as seen in FIG. 2, in which positionthe proximal and distal leg portions 30 and 32 form with the screw S asubstantially right angled triangle.

Additionally, the shank 20, for instance inwardly of (i.e. within) thelegs 24, may include a stopper which, for example, extends around thescrew S and which extends rearwardly from a proximal end of the distaltip 12 (examples of stoppers are shown at 234 and 334 of the furtherembodiments of FIGS. 5 and 6 and FIGS. 7 and 8, respectively). Such astopper does not extend the full length of the legs 24 when they are intheir collapsed position of FIG. 1, such that a proximal end of thestopper engages, in FIG. 2, the non-visible surface of the wall Winwardly of the proximal leg portions 30 of the legs 24 and/or the innerends of the proximal leg portions 30, thereby significantly impedingfurther retraction of the distal tip 12 towards the wall W. Even thoughthe proximal leg portions 30, when they engage the non-visible surfaceof the wall W, offer resistance to such a further retraction of thedistal tip 12, over-rotation of the screw S could cause the proximal legportions 30 to dig into the wall W. With the stopper, which is of alength which substantially correspond to the third side of the rightangled triangle that has the proximal and distal leg portions 30 and 32as its two other sides, it is ensured that the end position of the wallanchor 10 will be that illustrated in FIG. 2. In other words, theproximal leg portions 30 and/or the stopper will substantially preventthe screw S from being over-rotated.

FIGS. 1b, 2b, 1c and 2c show alternate shanks which, instead of havingfour legs 24 as in FIGS. 1 and 2, have five and three such legs,respectively. Other numbers of legs can also be contemplated.

FIGS. 3 and 4 illustrate a second wall anchor 110, also in accordancewith the present invention, which is similar to the first wall anchor10, except that a shank 120 of the wall anchor 110 includes a thread 121therearound that is substantially continuous with the threads 114 and122. Also, in the wall anchor 110, the proximal and distal leg portions130 and 132 of the legs 124 thereof are of a same length such that theyassume the general flattened end position shown in FIG. 4, with thethreads 121 of the proximal leg portion 130 engaging the non-visiblesurface of the wall W. In FIGS. 3 and 4, the screw S that is illustratedhas a larger pitch wood-type thread that makes the installation of thescrew S (including the expansion of the wall anchor 110) faster, i.e.with less rotations being required from the screw S. As for the firstwall anchor 10, the second wall anchor 110 includes a distal tip 112, anopening 116, a head 118 and a tapped section 128, and can also includefrangible films 126, such as frangible films 26 of the first wall anchor10.

FIGS. 3b, 4b, 3c and 4c show variations of the wall anchor 110, i.e.with five and three legs instead of the four legs 124 shown in FIGS. 3and 4.

As a variant to the second wall anchor 110 (and possibly also to otherwall anchors, e.g. to the first wall anchor 10), the section 128 of theshank 120 can include a metal insert provided with inner threads (i.e.it does not need to be tapped by the screw S) and mounted, for instancemolded, into the plastic shank 120 of the wall anchor 110, the innerthreads of such a metal insert (which acts as a nut) being typicallyadapted to receive a machine screw.

FIGS. 5 and 6 illustrate a third wall anchor 210, which is somewhatsimilar to the first wall anchor 10, except that it includes only two,diametrically opposed, legs 224. A pair of stoppers 234 are part of theshank 220 and extend between the legs 24 and rearwardly from a proximalend of the distal tip 212. The proximal ends of the stoppers 234 areadapted to limit the retraction of the distal tip 212 towards the head218 such that the wall anchor 210 assumes, in its final position, thegeneral configuration shown in FIG. 6.

The wall anchor 210 further includes a distal thread 214, a distalopening 216, a proximal thread 222, a tapped section 228 and proximaland distal leg portions 230 and 232.

FIGS. 7 and 8 illustrate a fourth wall anchor 310 in which a stopper 334takes the form of a cylinder that extends rearwardly from the distal tip312 and within the legs 324. The stopper 334 can take the form, asillustrated, of a rearward extension of the tapped section 328 such thatit is also tapped by the screw S. The number of legs 324 in the shank320 can vary, as seen for instance in FIGS. 7a and 8a, 7b and 8b, and 7cand 8c where four, five and three legs are illustrated, respectively.

The fourth wall anchor 310 also includes a distal thread 314, a distalopening 316, a proximal head 318, a proximal thread 322 and proximal anddistal leg portions 330 and 332. Frangible sections can also be providedbetween adjacent legs 324, as in the first wall anchor 10 of FIGS. 1 and2.

FIGS. 9 and 10 illustrate a fifth wall anchor 410 also in accordancewith the present invention, which is similar to the first wall anchor 10of FIGS. 1 and 2, but which shows a variant distal tip 412 that is basedon the distal section of the self-drilling anchor of aforementioned U.S.Pat. No. 5,234,299. The distal tip 412 of the wall anchor 410 could alsotake the shape of the blade of the self-drilling threaded insert ofaforementioned U.S. Pat. No. 4,601,625. In fact, these variant distaltips as well as others can be contemplated for the various wall anchorsdisclosed herein.

With the illustrated distal tip 412, the wall anchor 410 is initiallypunched through the wall W before being rotated such that the proximalthreads 422 thereof engage the wall W. The wall anchor 410 also includesa head 418, a shank 420, legs 424, frangible films 426, a tapped section428 and proximal and distal leg portions 430 and 432.

FIGS. 9a and 10a show the shank 420 having four legs 424 as in FIGS. 9and 10, whereas FIGS. 9b, 10b, 9c and 10c show alternate legconfigurations consisting of five and three legs 424.

In FIGS. 11 and 12, a sixth wall anchor 510 is shown, wherein a shank520 includes side-by-side legs 524 which are slightly angled withrespect to a longitudinal axis of the wall anchor 510 and in a directionthat is opposite the torque exerted when the wall anchor 510 isrotatably inserted in the wall W in order to provide added rigidity tothe shank 520 during the rotary installation of the wall anchor 510. Thelegs 524 are detachably connected together by way of frangible portions526 which, as in previous embodiments, provide additional rigidity tothe shank when compared to legs that are not initially connectedtogether. The shank 520, as the shank 120 of FIGS. 3 and 4, includes athread 521 that provides with the proximal thread 522 and the distalthread 514 a substantially continuous thread. Once expanded, as seen inFIG. 12, the wall anchor 510 defines a bundle that is in abutment withthe non-visible surface of the wall W, this bundle being formed by thedeformed legs 524.

The sixth wall anchor 510 also includes a distal tip 512, a distalopening 516, a proximal head 518 and a tapped section 528.

FIGS. 13 and 14 show a seventh wall anchor 610 in accordance with thepresent invention, which is similar to the first wall anchor 10, exceptthat two of its legs 624 expand inwardly, such legs being designated byreference numerals 634 in FIGS. 13 and 14. These inwardly deflectinglegs 634 act as a stopper to resist further retraction of the distal tip612 towards the wall W once the wall anchor 610 has generally assumedits second position shown in FIG. 14.

The wall anchor 610 also includes a distal thread 614, a distal opening616, a head 618, a shank 620, a proximal thread 622, frangible films626, a tapped section 628 and proximal and distal leg portions 630 and632.

FIGS. 15 and 16 show an eighth wall anchor 710 in accordance with thepresent invention that consists of two separate components and, moreparticularly, of a threaded anchor section 711 (shown in isolation inFIG. 17) and an expandable locking member 724 (shown in isolation inFIG. 18). The anchor section 711 includes a distal tip 712, a distalthread 714, a distal opening 716, a proximal head 718, a shank 720, anda proximal thread 722.

The locking member 724 is initially collapsed, as seen in FIG. 15, beingpartly received in longitudinal grooves defined on diametrically opposedsides of the shank 720. The locking member 724 defines a pair of notches726 that are adapted to engage a proximal end of the shank 720, when thelocking member 724 is collapsed, wherein tips 728 defined by the notches726 are held inwardly of the shank 720. The locking member 724 alsoincludes a distal cylindrical member 730 that can be tapped by the screwS.

Once the screw S has been sufficiently inserted in the anchor section711, it contacts the locking member 724 and displaces it axially awayfrom the head 718 thereby disengaging the tips 728 of the locking member724 from the shank 720 of the anchor section 711. As the locking member724 is spring loaded, its release from the shank 720 causes it toautomatically deploy to its position shown in FIG. 18. The cylindricalmember 730 of the locking member 724 is then tapped by the screw S andwith subsequent rotation of the screw S, the locking member 724 isretracted towards the wall W until it assumes the position shown in FIG.16. In fact, the locking member 724 basically acts as a toggle that isdisplaced between a collapsed idle insertion position (FIG. 15) and awall engaging expanded position (FIG. 16).

The locking member 724 is inserted by the manufacturer of the wallanchor 710 through the central bore of the anchor section 711, from thehead 718 towards the distal tip 712, that is until the collapsed lockingmember 724 extends partly in the longitudinal grooves of the shank 720while the tips 728 of the locking member 724 are prevented fromexpanding by the proximal end of the shank 722. Again, once the screw Shas been sufficiently inserted, it axially moves the locking member 724along the bore of the anchor section 711 until the tips 728 aredisengaged from the shank 720 and are spring biased exteriorly throughthe longitudinal grooves of the shank 720.

FIGS. 19 and 20 illustrate a ninth wall anchor 810 in accordance withthe present invention, which is characterized by having inside threads828 defined in the distal end of the shank 820 and, interruptingly, inthe open distal end 812. The threads 828 defined in the shank 820 arecontinuous, but the inside threads 828 defined in the distal tip 812 areinterrupted by the distal opening 816. The inside threads 828 of thewall anchor 810 are obviously adapted to be engaged by the outsidethreads of the screw S (not illustrated). This configuration providesmore threads in the wall anchor 810 that can be engaged by the threadsof the screw S thereby providing more strength at the level of theengagement of the screw S with the wall anchor 810, which thus preventsstripping of the threads 828 of wall anchor 810 when the screw S isfurther rotated in order to retract the distal tip 812 rearwardlytowards the wall for expanding the legs 824 provided on the shank 820.

A pin P is located in the anchor 810 and is used during the moldingprocess to define the female inside threads 128. The structure of thispin P and how it is used will be described in details hereinafter.

The wall anchor 810 also includes a distal thread 814, a proximal head818, a proximal thread 822, and a thread 821 around the legs 824 so asto provide, with the threads 814 and 822, a continuous outside malethread (although interrupted at the distal opening 816). A tube 834 isprovided in the shank 820 of the wall anchor 810 to provide morerigidity when the wall anchor 810 is installed in the wall.

FIGS. 22 to 26 show a tenth wall anchor 910 in accordance with thepresent invention, which is similar to that of FIG. 3 although the wallanchor 910 includes an inner thread 928 (as in FIG. 19) locatedinterruptingly inside the distal tip 912 and un-interrruptingly within acylindrical section 936 that extends axially between a distal end of theshank 920 and a proximal end of the distal tip 912. This inner thread928 is adapted to be engaged by the thread of the screw S upon rotationthereof, and once the screw S is prevented from further advancing intothe anchor 910 (e.g. because it has abutted item I or the head 918 ofthe anchor 910), further rotation of the screw S causes the distal tip912 to be axially and translationally drawn towards the head 918 therebycausing the deformation (i.e. outward expansion) of the legs 924 ontothe hidden face of the wall W. A longitudinal axis of the anchor 910 isdenoted by “A”, and such an axis characterizes each of the anchorsdescribed herein.

The provision of female threads 128 both in the cylindrical section 936and in the distal tip 912 increases the overall female thread lengththat can be engaged by the threads of the screw S thereby providing morestrength at the level of the engagement of the screw S with the wallanchor 910, which thus prevents stripping of the threads 928 of wallanchor 910 when the screw S is further rotated in order to retract thedistal tip 912 rearwardly towards the wall for expanding the legs 924provided on the shank 920.

FIGS. 27a to 27d illustrate the installation sequence of the presentanchors and will now be described with reference to the tenth wallanchor 910. As seen in FIG. 27a , the wall anchor 910 is positioned withits distal tip 12 against the visible side of the wall W, and it isrotatably engaged therein using an appropriate torque-inducing tool,such as a screwdriver, having a bit formed to fit in the recess definedin the head 918 of the anchor 910. Here, a Phillips-type screwdriver bitB is used to fit into the cruciform recess 919. The anchor 910 isrotated until its head 918 abuts the visible side of the wall W, as seenin FIG. 27b . The screw S is then rotatably engaged in the wall anchor910 using the screwdriver bit B and the screw translationally advanceinto the wall W until it reaches its position shown in FIG. 3, whereatit is prevented from further advancing by the item I thinly abutting thewall W. As explained above and as seen in FIG. 27c , subsequent furtherrotation of the screw S causes, in view of the male threads of the screwS being engaged with the female threads 928 of the anchor 910, thedistal tip 912 to be axially and translationally drawn towards the head918, thereby causing the deformation (i.e. outward expansion) of thelegs 924 onto the hidden face of the wall W and firmly securing theanchor 910 to the wall W. As seen in FIG. 27d , such a deformationresults in some of the threads 921, provided around the arms 924,engaging (e.g. piercing into) the hidden face of the wall W.

FIGS. 28 and 29 illustrate the tenth anchor 912 of FIG. 23 with a corepin P therein that is used during the molding thereof to form thethrough passage extending axially through the anchor 910, including theinner threads 928 thereof. More particularly, the core pin P includes amain pin section 1000 (also shown in isolation in FIGS. 30 and 31) thathas a first portion 1002 adapted to form the inside of the head 918, ofthe expandable legs 924 and of the part of the shank 920 that extendsbetween the head 918 and the expandable legs 924, and a second portion1004 adapted to form the female threads 128 of the cylindrical section936. The core pin P also includes a secondary pin section 1006 that isadapted to form the threads 928 located in the distal tip 912 of theanchor 910. A distal end 1008 of the second portion 1004 of the main pinsection 1000 is shaped so as to mate with a proximal end 1010 of thesecondary pin section 1006, and this ensures the alignment of the mainpin section 1000 and the secondary pin section 1006, and thus a femalethread 128 that is substantially uninterrupted at a junction of where itwas formed by the main pin section 1000 and where it was formed by thesecondary pin section 1006, and that has a constant pitch.

The mold also includes two outer mold sections that will provide theshape to the outside of the anchor 910, and once the plastic has beeninjected in the mold, the main pin section 1000 is pulled out axiallyand translationally from the mold, while the secondary pin section 1006is removed laterally from the distal end 912, i.e. through the opening916 thereof. It is noted that the main pin section 1000 is pulled outfrom the mold during a specified period after the injection process,such that the main pin section 1000 does not strip the female threads128 that is has molded, these female threads completely solidifyingafter the main pin section 1000 has been so removed. In the priortechniques, the pin would be rotatably removed from the molded anchor,which is much more time consuming than the present translationalwithdrawal thereof.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An anchor for mountingto a hollow wall, comprising a proximal end adapted to be engaged by arotatable tool to rotate said anchor about a longitudinal axis thereofand to cause it to gradually engage a wall, a distal end adapted to cutthrough the wall as said anchor is rotated, and a shank between saidproximal and distal ends, said shank including at least one expandableleg, said expandable leg being in a collapsed position thereof when saidanchor is rotated to mount it to the wall and being located distallypast a rear surface of the wall once said anchor is mounted to the wall,said anchor including outer threads, said anchor being adapted toreceive therein a threaded fastener and to threadably engage thethreaded fastener distally of said leg such that sufficient rotation ofthe threaded fastener retracts said distal end towards said proximal endthereby causing said leg to displace to a laterally expanded positionthereof, and wherein said outer threads include a first outer threadprovided around said leg.
 2. An anchor as defined in claim 1, whereinsaid shank comprises, distally of said leg, a tubular section defining afirst inner thread adapted to be threadably engaged by the threadedfastener.
 3. An anchor as defined in claim 2, wherein said distal enddefines a second inner thread adapted to be threadably engaged by thethreaded fastener.
 4. An anchor as defined in claim 3, wherein saidfirst and second inner threads are substantially continuous and have asame pitch.
 5. An anchor as defined in claim 1, wherein said outerthreads include a second outer thread provided on said shank betweensaid proximal end and said leg and engaged in the wall when said anchoris in said first position.
 6. An anchor as defined in claim 5, whereinsaid outer threads include a third outer thread provided between saidleg and said distal end.
 7. An anchor as defined in claim 6, whereinsaid shank comprises, distally of said leg, a tubular section adapted tobe threadably engaged by the threaded fastener, said third outer threadbeing provided around said tubular section.
 8. An anchor as defined inclaim 6, wherein said first, second and third outer threads having asame pitch.
 9. An anchor as defined in claim 6, wherein there areprovided at least two said legs adapted to extend in differentdirections in said expanded position, said first outer thread extendingaround all of said legs in said collapsed position.
 10. An anchor asdefined in claim 1, wherein said proximal end comprises a flanged headdefining a recess for engageably receiving the rotatable tool.
 11. Ananchor as defined in claim 1, wherein there are provided at least twosaid legs, said legs extending substantially parallelly in saidcollapsed position.
 12. An anchor as defined in claim 11, wherein saidlegs are connected together in said collapsed position by frangibleelements adapted to rupture when the threaded fastener draws said distalend towards said proximal end, thereby allowing said legs to deploy tosaid expanded position.
 13. An anchor for mounting to a hollow wall,comprising a proximal end adapted to be engaged by a rotatable tool torotate said anchor about a longitudinal axis thereof and to cause it togradually engage a wall, a distal end and a shank between said proximaland distal ends, said shank including at least one expandable leg, saidexpandable leg being in a collapsed position thereof when said anchor isrotated to mount it to the wall, said anchor including an outer threadprovided around said leg, said anchor being adapted to receive therein athreaded fastener and to threadably engage the threaded fastenerdistally of said expandable leg such that sufficient rotation of thethreaded fastener retracts said distal end towards said proximal endthereby causing said expandable leg to displace to a laterally expandedposition thereof behind the wall.
 14. An anchor for mounting to a hollowwall, comprising a proximal end adapted to be engaged by a rotatabletool to rotate said anchor about a longitudinal axis thereof and tocause it to gradually engage a wall, a distal end adapted to cut throughthe wall as said anchor is rotated, and a shank between said proximaland distal ends, said shank including at least one expandable leg, saidexpandable leg being in a collapsed position thereof when said anchor isrotated to mount it to the wall and being located distally past a rearsurface of the wall once said anchor is mounted to the wall, said anchorincluding outer threads, said anchor being adapted to receive therein athreaded fastener and to threadably engage the threaded fastenerdistally of said leg such that sufficient rotation of the threadedfastener retracts said distal end towards said proximal end therebycausing said leg to displace to a laterally expanded position thereof,wherein said outer threads include a first outer thread provided aroundsaid leg.
 15. An anchor as defined in claim 14, wherein said outerthreads include a second outer thread provided between said leg and saiddistal end.
 16. An anchor as defined in claim 15, wherein said first andsecond outer threads have a substantially same pitch.
 17. An anchor asdefined in claim 15, wherein said outer threads include a third outerthread provided on said shank between said proximal end and said leg andengaged in the wall when said anchor is in said expanded position. 18.An anchor as defined in claim 17, wherein said first, second and thirdouter threads have a substantially same pitch.
 19. An anchor as definedin claim 15, wherein said shank comprises, distally of said leg, atubular section adapted to be threadably engaged by the threadedfastener, said second outer thread being provided around said tubularsection.
 20. An anchor as defined in claim 14, wherein there areprovided at least two said legs adapted to extend in differentdirections in said expanded position, said first outer thread extendingaround all of said legs in said collapsed position.